气固固循环流化反应器的流体力学行为

简单介绍了气固固三相反应设备的研究现状,描述了气固固循环流化反应器的操作特点,实验研究了气固固循环流化反应器的流体力学行为,如气固两相通过填料层的压降、细颗粒的固含率及细颗粒的质量流率等．     

气固固循环流化床密相床层压力脉动研究

在不同实验条件下研究了气固固循环流化床密相床层的压力脉动。压力脉动的情况表明：细颗粒的循环及循环量对粗颗粒的流体力学行为有很大影响。气速越低,影响程度越大。     

循环流态化：（Ⅱ）气—固流动规律

循环流态化气、固两相流动行为是比较复杂的,它不仅取决于气体速度、颗粒循环速率以及气、固物性;而且受设备条件(床层直径、床层高度、进、出口结构、内部构件等),操作温度和压力等因素的影响。循环流态化气、固流动的基本特征,表现在局部结构上是存在颗粒的聚集现象,表现在整体结构上为存在颗粒浓度、气体、固体运动速度等的轴、径向不均匀分布。这种局部和整体宏观上的不均匀性,相互影响,相互关联,是表征循环流态化气、固两相流动行为的重要因素,也是研究和改善循环流化床反应器的基本课题。     

GLS-LR中相含率与循环液速的研究进展

介绍了气液固三相环流反应器(GLS-LR)的工作原理及类型,概述了GLS-LR的气含率、固含率、循环液速等特性参数的测量方法,并指出了其优缺点;讨论了这三个特性参数随操作条件的变化规律;汇总并评述了气含率与循环液速的预测模型。     

低倍率循环流化床锅炉气固分离装置的研究

循环流化床锅炉气固分离装置是其关键部件,其主要作用是将大量高温固体物料从气流中分离出来,送回燃烧室,以维持燃烧室的快速流态化状态,以保证燃料与脱硫剂多次循环、反复燃烧和反应。本文将讨论低倍率循环流化床锅炉气固分离装置与循环倍率及其本身固有性能。     

气固循环流化床全回路数值模拟研究进展

气固循环流化床具有良好的混合、传热、传质、反应特性,同时还具有处理量大、可连续生产等优点,在众多领域均有广泛应用。气固循环流化床是一个由多个单元连接组合形成的循环回路,各单元间相互耦合、相互影响。对整个循环流化床系统进行全回路数值模拟,不仅能够获得更全面和详实的结果,而且在揭示系统流动规律和探究各单元内、单元间、单元与系统间的相互作用上具有独特优势。近十年来,以气固循环流化床全系统为模拟对象的全回路数值模拟研究逐渐兴起。本文对气固循环流化床全回路数值模拟方法的研究进展进行综述,对该方法的应用情况进行详细介绍,并对方法中采用的模型及相应特点进行逐一分析。循环流化床全回路系统同时存在多种流态,有待于建立适用于全回路系统的多流态物理模型（气固曳力模型与固相应力模型）。随着计算能力的提高以及物理建模的不断发展,全回路模拟方法将不断完善并发挥出更大的作用。     

气液固三相环流反应器的研究进展

综述了气液固三相环流反应器的类型及工作原理、气液固三相环流反应器的特性参数(气含率、固含率、循环液速、液相体积传质系数、轴向分散系数)的测量方法和影响因素，介绍了特性参数的数学模型。并对现有模型进行了评述。对今后的研究提出一些建议。     

循环流化床下料管中气固流动模型的研究

本文在下料管（内径100mm）的循环流化床内研究了气固流动规律。通过测定颗粒速度、颗粒浓度以及气体速度，进一步描述了气固相对速度与颗粒浓度的变化关系，在对气固相互作用分析的基础上，得到了描述气固下行流动的R－Z方程。     

同轴双锥两级气固快速分离器冷态实验研究

下行循环流化床反应器要求气固分离器具有分离效率高、气相停留时间短、压力损失小、设备磨损小等特点。利用气固二相在惯性上的差别,提出了一种新型同轴双锥两级气固快速分离器,并以FCC(F lu id Catalytic Crack ing)为循环物料对该型分离器的分离特性进行了研究。结果表明,同轴双锥两级气固分离器的分离效率在98%以上,气固分离器的压力损失在100 Pa以下,设备磨损小,能够满足下行循环流化床反应器的要求。     

高长径比三相内环流反应器中细颗粒相含率和循环液速的分布研究

在高径比为22的三相内环流反应器中,在常温常压下以空气-水-石英砂为物系,研究了在不同粒径下上升区固含率、下降区固含率和上升区循环液速随表观气速的变化规律和不同粒径下轴向固含率的分布情况,以及在固体体积分数不同的条件下,平均气含率和上升区气含率随表观气速的变化情况。结果表明:当粒径(ds)≤0.3 mm时,上升区固含率随表观气速的增加呈平缓变化趋势,下降区固含率随表观气速的增加而增加;当0.3 mm相似文献   

PARTICLE CONCENTRATION AND SIZE MEASUREMENTS IN TWO-PHASE TURBULENT COAXIAL JETS

Particle concentration and particle size distributions have been measured for two-phase (solid/air) turbulent coaxial jets using the Laser Diffraction Method (LDM) and a tomography data transform technique. Effects of velocity ratio, particle loading ratio, and particle size on the dispersions of gas and particles were determined. Experimental results show that the gas disperses much more rapidly than the particles and particle dispersion decreases with increasing in particle size. Increasing velocity ratio significantly increases gas dispersion, while effects of other variables are less significant. The mean particle size at the jet edge is about 15-20% smaller than that at the jet centerline. The turbulent Schmidt number Sc_p for two-phase turbulent coaxial jets ranges from 1.4 to 1.5.     

移动床除尘器捕集颗粒喷动再生的主要操作因素

通过对喷动再生操作前后的捕集颗粒进行采样,考察粉尘/捕集颗粒比、提升管气速、颗粒循环量等操作因素对再生效果的影响。结果表明,粉尘/捕集颗粒比、提升管气速、颗粒循环量为影响喷动再生效果的主要操作因素,随粉尘/捕集颗粒比增大、提升管气速增大、颗粒循环量减小,粒级效率增大;喷动再生器在提升管气速较高时,再生效率较高,但若提升管气速过高,捕集颗粒同样会随灰尘一起被带出;喷动再生过程不可避免地造成捕集颗粒的磨损,合适的提升管气速对整个喷动再生系统至关重要,一般为捕集颗粒带出速度的1.1?1.3倍。     

计算机图像处理技术用于微粒的定量测量

基于ＰＣＩ总线的图像采集卡,采用计算机图像处理、人工智能技术实现了对颗粒的定量分析。详细阐述了颗粒定量分析技术及原理、系统组成和软件设计。测试结果表明,该法操作简便、测试速度快、重复性好     

TiN对Si3N4复合材料力学性能及电导率的影响

研究ＴｉＮ粒子对氮化硅材料力学和电导率的影响,发现ＴｉＮ粒子的引入,对基体材料能起到增韧补强的作用;在烧结过程中,ＴｉＮ和Ｓｉ３Ｎ４发生互熔,当ＴｉＮ粒子达到一定比例后,复合材料内形成导电网络,材料具有电导性。     

表面改性过程对空心玻璃微球性能的影响研究

空心玻璃微球是制备复合泡沫材料的关键原料,对其进行表面改性有利于改善复合材料的性能。但目前的研究甚少关注处理过程对微球性能的影响,不利于复合材料的进一步优化设计。因此,本文拟在制备空心玻璃微球的基础上,通过改变处理液组成、处理时间等条件,测试微球粒子密度、抗压强度等变化情况,研究改性过程对其性能的影响。实验结果表明,改性过程中水会侵蚀玻璃壳体,导致其粒子密度随处理时间的延长、酸度的增大而降低,抗压强度也随之下降。采用适当浓度的Al2(SO4)3水溶液处理微球可以在其表面形成新的膜层,改善抗压强度。     

气液固三相流化床反应器测试技术

在简述已有三相流化床测试技术的基础上,着重对近年来开发的测试新技术的基本原理及优缺点进行了分析,包括光纤探头技术、超声探头技术、放射颗粒跟踪技术、X射线颗粒跟踪测试技术、颗粒图像测速技术、电容层析成像技术、激光多普勒测速技术和相多普勒测速技术等,同时,展望了三相流化床测试技术的新方向.     

Modeling of particle growth and morphology in the gas phase polymerization of butadiene. II. Simulation and discussion

The improved multigrain model was used to simulate the gas phase polymerization of butadiene catalyzed by low‐, medium‐, and high‐activity catalysts, respectively. For the low‐activity catalyst, the mass and heat transfer resistances in the particle were negligible. The morphology of the polymeric particles was uniform. For the medium‐activity catalyst, the overall mass transfer effectiveness was > 90%, the maximal temperature rise was 8K, and the heat transfer resistance in the particle was negligible. Mass transfer resistance does not affect the morphology of product particle significantly. For the high‐activity catalyst, the overall mass transfer effectiveness was within the range of 70–96%, the morphology of the product particle was affected by the mass transfer resistance to some extent. The maximal temperature rise was 21K; the heat transfer resistance in the particle was negligible as well. However, there was some severe mass transfer resistance in the particle, and the maximal temperature rise was ≤ 30K for the large catalyst particle with the same activity. Thus, the polymeric particle morphology was comparatively poor, with the occurrence of particle softening and sticking. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 730–741, 2001     

丁二烯气相聚合过程中聚合物颗粒增长的动态研究

An experimental apparatus composed of microscope, video camera, image-processing, and mini reactor which can be used for real-time measurement of the growth of polymer particle in gas phase polymerization was built up to carry out dynamic study of gas phase polymerization of butadiene by heterogeneous catalyst based on neodymium(Nd). The studies of the shape duplication of polymer particles and catalyst particles and the growth rate of polymer paxticle were made. Results show that the appaxatus and procedure designed can be well utilizedto make dynamic observation and data collection of the growth of polymer particle in gas phase polymerization.A phenomenon of shape duplication of polymer particles and catalyst particles was observed by the real-time measurement. The result also concludes that the activity of individual catalyst particle is different, and the effect of reaction pressure on the growth of polymer particle is significant.     

Modeling of particle growth and morphology in the gas phase polymerization of butadiene. I. Model and its solution method

An improved multigrain model designed to simulate the polymeric particle growth and morphology in the gas phase polymerization of butadiene was developed. In the model, the effects of intraparticle heat and mass transfers, heat and mass transfer resistances at the particle boundary layer, sorption of 1,3‐butadiene in 1,4‐cis‐polybutadiene, and intrinsic kinetics on the polymeric particle growth and morphology were considered. An improved numerical method was also proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 719–729, 2001     

气溶胶细粒物对大气能见度影响的研究

文章介绍了国内外关于气溶胶细粒物对大气能见度影响的研究情况,总结出研究中存在的问题,并针对仍存在的问题提出建议与展望。